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Old 09-16-2010, 09:39 AM
  #18451  
mschulz531
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Default RE: Welcome to Club SAITO !

This is probably a dumb question for you Saito experts out there, but I was given a Saito FA-72 engine in pieces. I sent the case to Horizon to replace the bearings (which the giver told me was all I needed to do to get the engine running again). Now I'm looking at putting the engine back together. I ordered the engine gasket set which arrived with my case which contains brand new bearings. Thanks Horizon! I'm looking at reassembling the engine..I've got the user manual with the parts explosion and I've read some posts on this forum and other places about the cam timing and how to do that.
Anyway, here are my questions:
How do I tell top from bottom on the cam pushrods? From the manual, it appears that the "fatter" end of the cam pushrod goes on the bottom and the "pointy" end goes on top. Am I interpreting the diagram correctly?
How do I tell front and back on the piston connecting rod? From the manual, it appears that the "flush" side of the piston connecting rod goes towards the carburetor side.
How do I get the "taper collet and drive flange" back on to the crankshaft. I've tried to "test fit" the drive flange back onto the crankshaft and it appears to be very tight. As far as I can tell, the taper collet is already in place on the drive flange...do I have remove or replace the taper collet as part of reassembling the engine?
The (plastic?) rear cover of the engine appears worn (on the inside)...is this something I should replace, or is this type of wear normal?
I have one part that I cannot identify on the diagram...it is a flat piece of aluminum or other very light metal. It is round in shape and appears to be about the same diameter as the rear cover. In a circular arrangement around the center of this part are "partially punched out" areas that are "half-circular" in shape. If this description is not clear, let me know and I will take a picture tonight and post it in a follow up.
The engine parts I was given did not include a muffler...I see that Horizon has two options for a basic muffler: an older, "cannister shaped" muffler, and a newer muffler which has the smaller front end and the larger back end. Any reason I should choose one over another?
I've tried to do as much research up front as possible so I wouldn't ask stupid questions, so thanks for your patience if you've previously answered these questions.
Sincerely,
Mike
Old 09-16-2010, 09:53 AM
  #18452  
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Default RE: Welcome to Club SAITO !

Mike,

The round piece with the partial punches is probably the muffler baffle. Sounds like it.

The push rods are more blunt, or rounder on the bottom. Use the more pointed ends for the top to fit against the rocker arm.

The connecting rod should have one side that is cut with a bevel. This is the chamfer. The chamfer is beveled like that so it will fit smoothly on the crank pin. Look at your rub patterns. You should see crankshaft rubs that match up to the con rod, and also the chamfer that goes against the crank pin.

You can pull the drive washer tight when you tighten down a prop. Sometimes they are loud as they snap in place.

The weak point in the older .72 is the plastic backplate. There is a newer aluminum plate that solves the flexing problems that caused air leaks at the manifold fitting. You need to get the Saito .91 carb screws for this backplate. This upgrade is very much worth the money and may save hours of headaches.
Old 09-16-2010, 09:55 AM
  #18453  
Hobbsy
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Default RE: Welcome to Club SAITO !

Simlpy slide the collet on the shaft to where it stops put ptiop driver ona tighten something up against it. The upper ends of the pushrods are fairly sharp pointed.
Old 09-16-2010, 12:09 PM
  #18454  
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Default RE: Welcome to Club SAITO !


ORIGINAL: mschulz531

"How do I tell top from bottom on the cam pushrods? From the manual, it appears that the "fatter" end of the cam pushrod goes on the bottom and the "pointy" end goes on top. Am I interpreting the diagram correctly?"

The pushrods on some of the Saito, like the FA 180, are the same on both ends. But, I don't know about your engine.


"How do I get the ''taper collet and drive flange'' back on to the crankshaft. I've tried to ''test fit'' the drive flange back onto the crankshaft and it appears to be very tight. As far as I can tell, the taper collet is already in place on the drive flange...do I have remove or replace the taper collet as part of reassembling the engine
"


I may be wrong, but I think that you are saying that the split collet is very tight in the prop driver (drive flange)? It needs to be removed form the prop driver (drive flange) so it is a loose fit in it. As the prop driver (drive flange) and collet are placed on the crankshaft and tightened down, the collet will be compressed by the prop driver to be tight on the crankshaft and secure the prop driver and crankshaft together.

To loosen the collet in the prop driver, I would use a piece of tubing or small socket that is slightly SMALLER than the inside diameter of the prop driver but BIGGER than the collet and tap it out the engine side of the prop driver.



Good luck.

Sincerely,

Richard
Old 09-16-2010, 12:22 PM
  #18455  
mschulz531
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Default RE: Welcome to Club SAITO !

ORIGINAL: spaceworm

ORIGINAL: mschulz531

"How do I get the ''taper collet and drive flange'' back on to the crankshaft. I've tried to ''test fit'' the drive flange back onto the crankshaft and it appears to be very tight. As far as I can tell, the taper collet is already in place on the drive flange...do I have remove or replace the taper collet as part of reassembling the engine
"

I may be wrong, but I think that you are saying that the split collet is very tight in the prop driver (drive flange)? It needs to be removed form the prop driver (drive flange) so it is a loose fit in it. As the prop driver (drive flange) and collet are placed on the crankshaft and tightened down, the collet will be compressed by the prop driver to be tight on the crankshaft and secure the prop driver and crankshaft together.

To loosen the collet in the prop driver, I would use a piece of tubing or small socket that is slightly SMALLER than the inside diameter of the prop driver but BIGGER than the collet and tap it out the engine side of the prop driver.



Good luck.

Sincerely,

Richard
Richard,
You are indeed correct - I am saying that the taper collet is very tight in the prop driver. I will separate the taper collet from the drive flange as you suggest and then place the taper collet and drive flange on the shaft separately. Thanks for the info.
-Mike


Old 09-16-2010, 12:33 PM
  #18456  
JoseN
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Default RE: Welcome to Club SAITO !

Mike:

I'm sure this is going to help you. It is for a .91 but all Saito engines are almost the same. It helped me a lot in a very similar situation.

Good luck.

Pepe

http://www.authorstream.com/Presenta...pt-powerpoint/
Old 09-16-2010, 12:36 PM
  #18457  
mschulz531
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Default RE: Welcome to Club SAITO !

blw,

You mentioned that the piece with the partial punches in it might be the muffler baffle...I'm not sure I understand this...is the muffler baffle listed anywhere in the exploded parts diagram of the Saito Small-Medium single cylinder manual anywhere? The size of this mysterious item is roughly the same diameter as part#17 - the rear cover - so I'm not sure how it would be part of the muffler. I'll post a picture once I get home tonight.

The connecting rod does have one side that is cut with a bevel (chamfer)...based on the exploded parts diagram, the orientation of the connecting rod appears to be with the bevel facing the front of the engine and the "flat" side of the connecting rod facing the rear of the engine. The diagram also appears to show the "thicker" part of the bevel at the top (connected to the piston) and the "thinner" part of the rod at the bottom, connecting to the pin on the crankshaft.

Regarding the backplate, it sounds like I do need to replace this. After reading your response and some other threads it sounds like this was definitely a weak part of the design and could have perhaps been what caused the previous owner of this engine to get frustrated with it and give it to me. (:>) Lucky me...I don't mind doing research. For the cost of new bearings, a new backplate, and a muffler, I get a working Saito .72 out of the deal. Of course, without the generous help and experience of the folks monitoring this forum, it would still be a bucket of useless parts! So thanks again for everyone's help. I will see if I can find the optional backplate and carb screws at Horizon and order them at the same time as my muffler.

-Mike

ORIGINAL: blw

Mike,

The round piece with the partial punches is probably the muffler baffle. Sounds like it.

The push rods are more blunt, or rounder on the bottom. Use the more pointed ends for the top to fit against the rocker arm.

The connecting rod should have one side that is cut with a bevel. This is the chamfer. The chamfer is beveled like that so it will fit smoothly on the crank pin. Look at your rub patterns. You should see crankshaft rubs that match up to the con rod, and also the chamfer that goes against the crank pin.

You can pull the drive washer tight when you tighten down a prop. Sometimes they are loud as they snap in place.

The weak point in the older .72 is the plastic backplate. There is a newer aluminum plate that solves the flexing problems that caused air leaks at the manifold fitting. You need to get the Saito .91 carb screws for this backplate. This upgrade is very much worth the money and may save hours of headaches.
Old 09-16-2010, 01:04 PM
  #18458  
mschulz531
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Default RE: Welcome to Club SAITO !

What appears to be the correct aluminum rear cover for the FA-82B/FA-72 (http://www.horizonhobby.com/Products...rodId=SAI82B17)
was only $1 more than the stock rear cover (http://www.horizonhobby.com/Products...rodId=SAI7217A)

The FA-82B Rear Cover is listed for both AB and RR models...since RR is the FA-72, doesn't that suggest/imply that the original screws should work for this rear cover?

Also found this item "FA-72B Rear Cover": http://www.horizonhobby.com/Products...rodID=SAI72B17
which is listed as "Preorders being taken, due late October, 2010". wonder what that is...no image is available.

-Mike
Old 09-16-2010, 01:48 PM
  #18459  
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Default RE: Welcome to Club SAITO !

You need the longer screws. I forgot that you will need to make a gasket for the new backplate. That's easy.
Old 09-16-2010, 01:58 PM
  #18460  
mschulz531
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Default RE: Welcome to Club SAITO !

Longer screws...seems easy....but not so easy after browsing the Horizon Hobby site....

here's one option: http://www.horizonhobby.com/Products...ProdID=SAI6514
here's another option:http://www.horizonhobby.com/Products...rodID=SAI91S90but these are out of stock (:<)

can anyone give me info on the size/length of the screws I need?

Does the engine gasket set for the FA-72 include the new gasket for the rear cover?
I'm not at home so I can't see what's in the package...

-Mike
Old 09-16-2010, 03:03 PM
  #18461  
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Default RE: Welcome to Club SAITO !

ORIGINAL: blw
Mike,
The weak point in the older .72 is the plastic backplate. There is a newer aluminum plate that solves the flexing problems that caused air leaks at the manifold fitting. You need to get the Saito .91 carb screws for this backplate. This upgrade is very much worth the money and may save hours of headaches.
Did you mean "carb screws" or did you mean "crankcase screws"? I notice on the parts diagram that part # 31 is listed as "crankcase screw set" and these are the four screws that attach the backplate to the case.
The parts listing shows that the FA-72 uses part#82B31 for the crankcase screws but most of the other engines use part#5031 for the crankcase screw set.

The item I found on Horizon for the FA-91 is this one: http://www.horizonhobby.com/Products...ProdID=SAI5031
but these are crankcase screws, not carb screws, that's why I'm asking for clarification. Also, I'm hoping the picture for this item is just plain wrong because it shows one screw and one set screw...

Thanks,
Mike


Old 09-16-2010, 03:18 PM
  #18462  
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Default RE: Welcome to Club SAITO !

You will need the carb screw set for the Saito 50. Here is the number

http://www.horizonhobby.com/Products...rodID=SAI5090A

The reason you need these screws is that the original Saito 72 used sheet metal screws to attach the carb. With the metal back plate, you will need the regular Saito machine screws to attach the carb to the back plate.

You will also need to purchase a gasket or make one to go between the metal back plate and the crankcase. The original plastic back plate did not use a gasket

It is also a good idea to always put a new Viton O-ring on the intake manifold where it goes into the head

When attaching the carb to the back plate, hold the intake manifold tightly into the cylinder head as you are making the screws tight

Old 09-16-2010, 03:26 PM
  #18463  
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Default RE: Welcome to Club SAITO !


How many screws does the Saito .50 carb screw set contain? I only see two in the picture...don't I need four screws for the backplate?

I already purchased the engine gasket set for the 72; I'm pretty sure this includes the O ring that you mentioned, although there is already an O ring in place where the intake manifold goes into the head.

Any tips on how to make my own gasket?

Thanks,
Mike

Old 09-16-2010, 04:47 PM
  #18464  
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Default RE: Welcome to Club SAITO !

You can re-use the existing four back plate retention screws as they are the same.

You just need the two screws that hold the carb itself on.

The manifold O-ring you are interested in is the one in the small package within the big package that say "Viton" on it.
===================================
I make the back plate gasket from the card stock flap that the back plate came in.

I put the new back plate against the carb board and trace around the round part only with a ball point pen or pencil.

I cut out this round hole and adjust the hole to where the round part of the back plate will fit tightly into the hole.

I then assemble the back plate / cardboard onto the crankcase and start the screws. They will punch on through the card stock.

Snug up the back plate against the crankcase.

Trim off the part of the card stock that is sticking out from the crank case with a razor blade or Exacto knife.
Old 09-16-2010, 05:25 PM
  #18465  
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Default RE: Welcome to Club SAITO !

My bad on the .50 carb screws. I thought it was the .91 set.
Old 09-16-2010, 08:19 PM
  #18466  
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Default RE: Welcome to Club SAITO !

[Light bulb goes on]
Carb screws - got it! Because we are talking about connecting the carb to the backplate, not the backplate to the case.
I kept trying to figure out why I needed longer screws to connect the aluminum backplate to the case in lieu of the plastic backplate.
Suddenly it all makes sense!
Thanks for walking me through this until I "got it".
Regards,
Mike
Old 09-16-2010, 08:21 PM
  #18467  
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Default RE: Welcome to Club SAITO !

I've converted four of these over already so I've been there and done that.
Old 09-16-2010, 11:12 PM
  #18468  
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Default RE: Welcome to Club SAITO !

Ok, I'm posting a picture of the mystery part. This part came with my engine (parts in a plastic bag)
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Old 09-16-2010, 11:43 PM
  #18469  
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Default RE: Welcome to Club SAITO !

I finally got around to building my sig spacewalker 2 1/4 scale and just finished painting it.dry the the weight is likely close to 12 pounds.I have set it up using my satio 150.I hope the 150 will fly this plane well.I am trying to keep weight down and wondered if anybody knows what the fuel consumption is as I want to use a 12 ounce tank.I typically fly for 5 or 6 minutes at a time .I guess I am worried whether or not a 150 will fly this plane given its nearly 12 pounds.

please let me know..
Old 09-17-2010, 01:29 AM
  #18470  
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Default RE: Welcome to Club SAITO !

I think the SAITO 150 ,

for this type of airframe ,

will be just fine....personally i'd go with a 14-16oz tank
for the time you usually fly..
Old 09-17-2010, 05:38 AM
  #18471  
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Default RE: Welcome to Club SAITO !


ORIGINAL: mschulz531

Ok, I'm posting a picture of the mystery part. This part came with my engine (parts in a plastic bag)
This is not a Saito part

Old 09-17-2010, 07:22 AM
  #18472  
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Default RE: Welcome to Club SAITO !


ORIGINAL: mschulz531

Ok, I'm posting a picture of the mystery part. This part came with my engine (parts in a plastic bag)
Looks like a muffler baffle of some sort.
Old 09-17-2010, 09:45 AM
  #18473  
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Default RE: Welcome to Club SAITO !

I always think the plane will be too heavy but in this case the 150 should spacewalker around with ease.and I will add a 14 ounce tank.I was leaning toward 12 ounces.my flying style on this scale project will be a typical sunday flyer.I save on my 3d and crazy stuff for extra and gasser planes.I am likely going to build another scale plane and install my 180 which I love love .heck I love satios.the 180 loves fuel which is wwhy I had a concern about my 150.I suspect a 12 would be ok I am going to bump the fuel to 20 percent as I usually burn 15 percent.
Old 09-17-2010, 10:06 AM
  #18474  
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Default RE: Welcome to Club SAITO !

A Saito 150 is not far behind a 180 in fuel consumption

A Saito will burn 20% nitro fuel faster than it will 15% nitro fuel
Old 09-17-2010, 11:57 AM
  #18475  
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true .but I fly electrics and gas as well.I dumped all my 2 strokes except a couple.more and more I have gone eletric 3D but I continue to build scale .the fuel is just part of the hobby lol.

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